First, make sure the slider isn't set to hidden in the page meta settings.

Did you have any custom scripts or css inserted into the site which could be effecting the slider?

Are you getting any error messages anywhere, any css/parse errors in the admin bar?

Could you deactivate all plugins at once (instead of one by one) and see if the feature slider comes back, could be there's more than one conflict. Make sure all plugins are upto date and on the latest version as well.

If none of the above could you take a screen shot of your admin area and the drag and drop page, just in case we can notice anything else for you.

The only other option i can think of would be to set it up with text on the bottom and then hide the text using css. Try the below, change the number at the end of #feature_ to reflect the ID of the slide you have the video on.